Aneurysms are discrete dilations of the arterial wall. One of the most common, and among the most life threatening, is an aneurysm of the abdominal aorta between the renal and iliac arteries. If untreated, the aneurysm dilates progressively with an ever increasing risk of rupture and hemorrhagic death.
One method of treatment is provided by direct surgical intervention, in which the defective vessel may be bypassed or replaced using a prosthetic device such as a synthetic graft. The risks involved in direct surgical intervention of this magnitude are great, and include an extensive recovery period.
In recent years a less invasive method of treatment has evolved through a series of inventions. The details vary, but, conventionally, a resilient tubular conduit (herein referred to as a “graft”) is introduced into the defective vessel by means of catheters introduced into the femoral artery, and is attached to the non-dilated arteries above and below the aneurysm using expandable metallic or plastic cylinders (herein referred to as “attachment systems”).
However, the use of generally cylindrical grafts to reinforce vascular walls in a patient is not without problems. The known methods for delivering grafts to the required location within a patient's vascular system conventionally require that an attachment system be delivered simultaneously with the graft, axially overlapping the graft and located either on the interior or the exterior of the graft's lumen, so that upon deployment of the graft the attachment system is expanded to attach the graft to the vascular wall. In the prior art, the attachment system is typically connected to the graft before implantation in the patient by means such as stitching. Because grafts are conventionally required to be compressed into a capsule or sheath before being implanted in final position within the patient's vascular system, delivery capsules or sheaths must be sufficiently small to enable insertion into the patient's vessel, and, once inserted, must be sufficiently flexible to allow bending around corners and branches of the patient's vascular tree. Yet, as a consequence of the practice of delivering the attachment system simultaneously with and axially overlapping the graft, the outer diameter of the delivery capsule or sheath containing the compressed graft in such cases is increased by the presence of the compressed attachment system.
One of the problems encountered in the art of delivering grafts to the vascular system of a patient is that complications may be encountered in maneuvering the compressed graft and its delivery system around the bends and branches of the patient's vascular system. It will be appreciated that the greater the outer dimension of the capsule containing the compressed graft to be delivered, the more inflexible it will be, making delivery to the final destination more difficult and perhaps even impossible in some patients.
Another problem encountered in the art of graft delivery is that, in the majority of cases, the patient must be subject to surgery in which the appropriate vessel is surgically exposed and opened by incision to allow entry of the graft. Significantly, it is this surgical procedure on the vessel which gives rise to the most serious complications known in the art of minimally invasive graft delivery, with complications taking the form of infection, patient discomfort, and necrosis of the vessel itself. However, if the outside dimension of the delivery capsule were sufficiently small, it might be possible, depending on the size and condition of the patient, to insert the capsule into the patient's vessel by applying sufficient force to the skin and artery of the patient with a sharpened end of the graft's delivery capsule, similar to the commonly known method of inserting a needle directly into the vein or artery of a patient.
There therefore exists a need to reduce the outside dimension of the capsule or sheath containing a compressed graft to be delivered to the patient's vascular system. This invention addresses these needs.